The present invention relates to an adapter for mounting a portable telephone on a vehicle and, more particularly, to an adapter for such an application which is adaptable to both of a simple handset and a multi-function handset available with a portable telephone.
A portable telephone is mounted on a vehicle with a handset thereof being usually set in a vehicle cabin by using an exclusive adapter. This kind of adapter has customarily been designed for use with a simple handset which does not have a power switch, dialing function, etc. The adapter, therefor, is provided with a power switch for feeding power to the portable telephone system as needed. The power switch of the adapter is accessible for controlling the power supply to the telephone system as well as for dialing purpose. A problem with such an adapter is that the power switch and its associated circuitry increases the overall weight and volume of the adapter while increasing the cost.
In the light of the above, an effort has been made to mount a multi-function handset on a vehicle in place of a simple handset so that the power supply may be controlled by the handset itself. However, when a multi-function handset is used with the prior art adapter which is directed toward a simple handset, it will fail to control the power supply depending on the arrangement of the power switch which is built in the adapter. Although the power switch of the adapter may be omitted, an adapter without a power switch would be unable to control the power supply when used with a simple handset.